Dangerous information here. Fresh eggs sink, they don't float. A very fresh egg will immediately sink to the bottom of a bowl of cold, unsalted water and lie flat on its side. This is because the air cell within the egg is very small. The egg should also feel quite heavy.

As the egg starts to lose its freshness and more air enters the egg, it will begin to float and stand upright. The smaller end will lie on the bottom of the bowl, while the broader end will point towards the surface. The egg will still be good enough to consume.

If the egg fully floats in the water and does not touch the bottom of the bowl at all, it should be discarded, as it will most likely be bad.